check out your input settings in edit > project settings > input. also have a look at this it will tell you all you need to know about the options you are faced with. http://unity3d.com/support/documentation/Manual/Input.html the unity manual is highly valuable and you should check there for some of the more basic stuff before asking a questions.

If you're using the standard FPS controller that comes with Unity 3, then there is are "sliding" variables on the character motor script which should allow you to deactivate sliding.